The Dzherman takes its source from the Tear Lake, the highest one of the
Seven Rila Lakes group in the western part of Rila at an altitude of 2,535 m. It then flows though the Twin Lake and the Trefoil Lake before continuing in northeastern direction, where it is joined by a stream flowing from the two lowermost lakes of the group, the Fish and the Lower Lakes. Within Rila, the river flows in a heavily forested deep glacial valley with a number of rapids and waterfalls. Initially the Dzherman flows in northeastern direction and at 1.3 km northwest of the Vada refuge, it makes a sharp turn to the northwest. It enters the
Dupnitsa Valley near the town of Sapareva Banya, where it turns to the west and its valley becomes wide and relatively shallow. After the town of Dupnitsa, the Dzherman, fed by its numerous tributaries mainly from the northwestern slopes of Rila, becomes larger, turns to the south-southwest and its valley widens significantly. It then flows into the
Struma, at an altitude of 369 m, about 1 km east of the town of Boboshevo. Its catchment area covers a territory of 392 km², or represents 4.43% of Struma's total. It borders the basins of the rivers Leva and Arkata, left tributaries of the Struma, to the west and north; the basin of the
Rilska River, a left tributary of the Struma, to the south; and basin of the
Iskar from the Danube drainage to the northeast and east. Its tributaries include Skakavitsa, Goritsa, Dupnishka Bistritsa, etc. The highest waterfalls in Rila are situated in the Dzherman catchment area —
Skakavitsa (70 m) and
Goritsa (39 m). The Dzherman has predominantly snow-rain feed with high water in late spring and early summer (May–June) and low water in summer (July–September). The average annual flow is 3.35 m3/s at Dupnitsa. == Settlements and transport ==